IC substrate with over voltage protection function

ABSTRACT

The present invention relates to an IC substrate provided with over voltage protection functions and thus, a plurality of over voltage protection devices are provided on a single substrate to protect an IC chip directly. According to the present invention, there is no need to install protection devices at respective I/O ports on a printed circuit board to prevent the IC devices from damage by surge pulses. Therefore, the costs to design circuits are reduced, the limited space is efficiently utilized, and unit costs to install respective protection devices are lowered down.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. Non-Provisional applicationSer. No. 10/463,984, filed Jun. 18, 2003, the entire contents of whichare incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an IC substrate with over voltageprotection functions, more particularly, to an IC substrate providedwith a structure having multiple over voltage protection devices.

BACKGROUND OF THE INVENTION

A conventional over voltage protection device is installed near I/Oports on a printed circuit board to protect internal IC devicesaccording to demands by each IC device. However, such design requiresinstalling independent over voltage protection devices in accordancewith requirements of respective circuits to prevent respective ICdevices from being damaged by surge pulses.

Please refer to FIG. 1 a, which is a top view of an IC device disposedon a conventional substrate. In FIG. 1 a, there are a plurality ofelectrodes (11) and a grounding line (13) disposed on a substrate (12).Then, an IC device (10) is soldered to the plurality of electrodes andthe grounding line. FIG. 1 b is a sectional view of the IC devicedisposed on the conventional substrate. In FIG. 1 b, we can understandthe relationship among the constituent elements. Because such structurecannot provide over voltage protection functions, the IC device cannotwithstand the energy of surge pulses, which result in an irrecoverabledamage to the IC device.

In order to protect the IC device, several over voltage protectiondevices are frequently proposed. However, those over voltage protectiondevices need to install individual protection devices on a printedcircuit board according to actual demands after the IC device wasmanufactured and installed near the I/O ports on the printed circuitboard. Therefore, such design has the disadvantages of high designcosts, wasting limited space, and providing incomplete protection forthe IC device.

Therefore, there is a need to provide an IC substrate with over voltageprotection functions. In this substrate, a plurality of over voltageprotection devices are provided simultaneously to solve the problemswith the prior arts that are unable to provide the over voltageprotection or to eliminate the inconvenience in the prior arts thatneeds to install individual protection devices on a printed circuitboard. The present invention provides an IC substrate with over voltageprotection functions to eliminate such inconvenience.

SUMMARY OF INVENTION

An object of the present invention is to provide an IC substrate withover voltage protection functions and a method for manufacturing thesame and thus, the IC device can be protected against the presence ofsurge pulses.

Another object of the present invention is to provide an IC substratewith over voltage protection functions and a method for manufacturingthe same, wherein the grounding lines are disposed on a lower surface ofa substrate and thus, the space is saved and the costs are reduced.

Still another object of the present invention is to provide a substratehaving a plurality of over voltage protection devices, so that thedesign costs are reduced, the space is saved and the unit costs need forinstalling protection device on the IC circuits are reduced.

Further still another object is to provide an IC substrate with overvoltage protection functions and a method for manufacturing the same,wherein the substrate can be designed by all kinds of IC packagingmethods, such as DIP and SMD.

Another object of the present invention is to provide an IC substratewith over voltage protection functions and a method for manufacturingthe same, wherein the protection circuits are installed after the IC ispackaged.

In order to accomplish the above objects, the IC substrate comprises asubstrate, and a grounding conductor layer for forming a groundingterminal. The grounding terminal is disposed on the lower surface of thesubstrate and extending to an upper surface of the substrate, thereby toexpose one or more terminals on the upper surface of the substrate. Oneor more variable resistance material layers are disposed on exposedterminals of the grounding conductor layer. The grounding conductorlayer terminals are electrically connected with the variable resistancematerial layers. A plurality of conductor layers form electrodeterminals. Each conductor layer is disposed on the substrate andoverlays on each of the variable resistance material, so as to form aconnection with each of the variable resistance material layers. Inpractical application, the substrate is made of ceramic substrate orPCB.

In order to understand the technical contents and features of thepresent invention with ease, the present invention is described byreferring to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be illustrated according to the followingdrawings, wherein:

FIG. 1 a is a top view of an IC device disposed on a conventionalsubstrate;

FIG. 1 b is a sectional view of an IC device disposed on a conventionalsubstrate;

FIGS. 2 a, 2 b and 2 c are sectional views of an IC substrate formedwith over voltage protection functions according to an embodiment of thepresent invention;

FIGS. 2 d and 2 e are top views of an IC substrate formed with overvoltage protection functions according to the embodiment of the presentinvention;

FIGS. 3, 4 and 5 are sectional views of an IC substrate formed with overvoltage protection functions according to another embodiment of thepresent invention;

FIGS. 6 a and 6 b are top views of a multi-layer IC substrate formedwith over voltage protection functions according to an embodiment of thepresent invention;

FIGS. 7 a, 7 b and 7 c are sectional views of a multi-layer IC substrateformed with over voltage protection functions according to an embodimentof the present invention;

FIGS. 8 a, 8 b, 8 c, 8 d and 8 e are sectional views of a BGA IC packageformed with over voltage protection functions according to an embodimentof the present invention;

FIG. 8 f is a top view of a BGA IC package formed with over voltageprotection functions according to an embodiment of the presentinvention;

FIGS. 9 a and 9 b are sectional views of the IC substrate with overvoltage protection functions according to an embodiment of the presentinvention; and

FIGS. 10 a, 10 b, 10 c, 10 d, 10 e and 10 f are sectional views of an ICsubstrate formed with over voltage protection functions according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of the present invention are described with reference tothe drawings. The same elements in the drawings have the same referencenumerals.

FIGS. 2 a, 2 b and 2 c are sectional views of an IC substrate formedwith over voltage protection functions according to an embodiment of thepresent invention. As shown in FIG. 2 a, a first conductor layer isformed to be a grounding conductor layer (23) on a substrate (22). Thefirst conductor layer is formed on a lower surface of the substrate andextends through the substrate to its upper surface. One or moreterminals are formed on the upper surface of the substrate. As shown inFIG. 2 b, one or more variable resistance material layers (24) areformed to overlay the terminals of the grounding conductor layer (23) soas to form connection with each of the variable resistance materiallayers. In addition, a plurality of second conductor layers (21) areformed to be upper electrodes. The second conductor layers overlay onthe variable resistance material layers (24) so as to form connectionwith each of the variable resistance material layers. FIG. 2 c is asectional view of an IC chip (20) disposed on the substrate. A chip (20)is connected with the upper electrodes (21) by soldering, and aprotection layer (25) is added to the chip to prevent from dust andmoisture. FIG. 2 d is a top view of the invention in FIG. 2 a. FIG. 2 eis a top view of the invention in FIG. 2 b.

FIG. 3 shows another embodiment of connecting an IC chip with the upperelectrodes by wire bonding.

FIG. 4 is a sectional view of an IC substrate (42) with over voltageprotection functions according to another embodiment of the presentinvention. As shown in FIG. 4, one or more variable resistance materiallayers (44) are formed on a substrate (42). The variable resistancematerial layers are disposed on the lower surface of the substrate. Agrounding conductor layer (43) is formed to be a grounding terminal. Thegrounding terminal is disposed on the lower surface of the substrate andextends to overlay on each of the variable resistance material layers. Aplurality of conductor layers (41) are formed to be electrodes. Theconductor layers are disposed on the upper surface of the substrate, andextend through the substrate to its lower surface so as to formconnection with each of the variable resistance material layers.

FIG. 5 is a sectional view of an IC substrate (52) with over voltageprotection functions according to further another embodiment of thepresent invention. As shown in FIG. 5, a grounding conductor layer (53)is formed on a substrate to be a grounding terminal. The groundingterminal is disposed on the lower surface of the substrate. One or morevariable resistance material layers (54) are disposed through thesubstrate and are connected with the grounding conductor layer. Aplurality of conductor layers (51) are formed to be electrode terminals.Each of the conductor layers are disposed on the upper surface of thesubstrate, and overlays each of the variable resistance material layersand is connected with them.

When a surge pulse occurs, the energy of the surge pulse will enter theelectrode terminals (51) to propagate to the grounding terminal (53)through the variable resistance material layers (54). Because the natureof the variable resistance materials and its structure, the energy ofthe surge pulse will be released evenly to the grounding lines and thus,the IC device (50) will not be damaged and the object to protect the ICdevice is achieved.

FIGS. 6 a and 6 b are top views of a multi-layer IC substrate formedwith over voltage protection functions according to an embodiment of thepresent invention. As shown in FIG. 6 a, one or more grounding conductorlayers (83) are formed on a first substrate (821) to be groundingterminals, which extend to a upper surface of the first substrate and isdisposed on the lower surface of the first substrate, thereby formingone or more terminals on the upper surface of the first substrate. Oneor more variable resistance material layer (84) are formed on the firstsubstrate (821) and overlay the terminals of grounding conductor layers(83) appeared on the substrate and are connected with each of thegrounding conductor layers. A plurality of first conductor layers (811)are formed on the upper surface of the first substrate (821). Each ofthe conductor layers (811) is disposed on the substrate and overlays oneach of the variable resistance material layers (84), so as to form anelectrical connection with each of the variable resistance materiallayers. The plurality of first conductor layers (811) extend through thefirst substrate (821), and terminals of the first conductor layer (811)appear on the upper and lower surfaces of the first substrate (821).

As shown in FIG. 6 b, a plurality of second conductor layers (812) areformed on a second substrate (822) to be electrode terminals. Theplurality of second conductor layers extend through the second substrate(822), and terminals of the second conductor layer appear on the uppersurface of the second substrate (822). The second substrate (822) isdisposed on the upper surface of the first substrate (821), wherein thefirst conductor layers (811) are electrically connected with the secondconductor layers (812). In FIG. 6 b, an IC chip (80) is disposed on thesecond substrate (822), and a protection layer (85) is added to thesecond substrate.

FIGS. 7 a, 7 b and 7 c are sectional views of forming a multi-layer ICsubstrate formed with over voltage protection functions according to anembodiment of the present invention. As shown in FIG. 7 a, a pluralityof first conductor layers (611) are formed on a first substrate (621).Each of the conductor layers (611) is disposed through the firstsubstrate, and terminals of the conductor layer appear on the uppersurface and lower surface of the first substrate (621). A plurality ofsecond conductor layers (612) are formed on a second substrate (622).Each of the conductor layers (612) is disposed through the secondsubstrate (622), and terminals of the conductor layer (612) appear onthe upper surface and lower surface of the second substrate (622). Holesare formed on the second substrate (622) and filled with one or morevariable resistance material layers (64). The variable resistancematerial layer (64) is disposed through the second substrate (622).Terminals of the variable resistance material layers appear on the uppersurface of the second substrate. A grounding conductor layer (63) isformed on the second substrate (622) to be a grounding terminal, whichis disposed on the lower surface of the second substrate. A plurality ofthird conductor layers (613) are formed on a third substrate (623) to beelectrode terminals. The plurality of third conductor layers aredisposed through the third conductor layers appear on the upper andlower surfaces of the third substrate.

As shown in FIG. 7 b, the second substrate (622) overlays the firstsubstrate (621). The lower portion of the variable resistance materiallayers (64) is connected with the grounding conductor layer (63). Theterminals (612) on the lower surface of the second substrate areconnected with the terminals (611) on the upper surface of the firstsubstrate (621). The third substrate (623) overlays the second substrate(622). The third conductor layer (613) is connected with the variableresistance material layer (64) and the terminals (612) on the uppersurface of the second conductor layer (612), respectively.

As shown in FIG. 7 c, an IC chip (60) is disposed on the third substrate(623). The chip (60) is connected with the upper electrodes bysoldering. A protection layer (65) is added to prevent from dust andmoisture.

Please note that the variable resistance material layers can be made ofnon-linear resistance materials.

FIGS. 8 a, 8 b, 8 c, 8 d and 8 e are sectional views of a Ball GridArray (BGA) IC package formed with over voltage protection functionsaccording to an embodiment of the present invention. FIG. 8 f is a topview of a BGA IC package formed with over voltage protection functionsaccording to an embodiment of the present invention.

As shown in FIG. 8 a, a plurality of grounding conductor layers (731,732, 733) are formed on a BGA IC package to be grounding terminals. Eachof the terminals is disposed on the surface of the BGA IC package. Asshown in FIGS. 8 b and 8 f, one or more variable resistance materiallayers (74) are formed on the plurality of grounding conductor layers(731, 732). Each of the variable resistance material layers is disposedon the terminals of the grounding conductor layers (731, 732) and isconnected with each of the grounding conductor layers. As shown in FIG.8 c, a plurality of variable resistance material layers (74) areconnected with electrode terminals (71) and grounding conductor layers(731, 732, 733). As shown in FIG. 8 d, a second protective layer (76) isdisposed on the electrode terminals and the variable resistancematerials layers. FIG. 8 e is a sectional view of an embodiment of thepresent invention after solders are added on the electrode terminals andthe grounding conductor layers.

FIGS. 9 a and 9 b are sectional views of the IC substrate with overvoltage protection functions according to an embodiment of the presentinvention.

FIGS. 10 a, 10 b, 10 c, 10 d, 10 e and 10 f are sectional views of an ICsubstrate formed with over voltage protection functions according to anembodiment of the present invention.

According to an embodiment of the present invention, a method forforming an IC substrate with over voltage protection functions comprisesthe following steps. As shown in FIGS. 10 a and 10 b, one or moredesired holes are formed in the substrate (102) by laser or punching. Asshown in FIG. 10 c, the holes are filled variable resistance materiallayers (104). As shown in FIG. 10 d, a lower electrode (103) is formedon the substrate. The lower electrode (103) overlays each of thevariable resistance material layers (104) and is connected with thevariable resistance material layers (104). As shown in FIG. 10 e, aplurality of upper electrodes (101) are formed on the upper surface ofthe substrate (102). Said upper electrodes (101) overlay each of thevariable resistance material layers (104) and are connected with thevariable resistance material layers (104). Said upper electrodes andlower electrodes are formed by printing or metal foil pressing. FIG. 10f is a sectional view of an IC chip (100) disposed on the substrate(102).

Although the invention has been disclosed in terms of preferredembodiments, the disclosure is not intended to limit the invention. Theinvention still can be modified or varied by persons skilled in the artwithout departing from the scope and spirit of the invention which isdetermined by the claims below.

1. An IC substrate with over voltage protection functions, comprising: asubstrate; a grounding conductor layer for forming a grounding terminal,said grounding terminal being disposed on the lower surface of thesubstrate; one or more variable resistance material layers disposedthrough the substrate and connected with the grounding conductor layers;and a plurality of conductor layers for forming electrode terminals,each conductor layer being disposed on an upper surface of the substrateand overlaying each of the variable resistance material layers, andconnected with each of the variable resistance material layers.
 2. TheIC substrate with over voltage protection functions of claim 1, whereinthe variable resistance material layers are non-linear resistancematerial layers.
 3. The IC substrate with over voltage protectionfunctions of claim 1, wherein the substrate are made of ceramicmaterials or polymer materials.
 4. The IC substrate with over voltageprotection functions of claim 1, wherein the electrode terminals areconnected with a chip by soldering or wire bonding.
 5. The IC substratewith over voltage protection functions of claim 1, further comprising aprotection layer for reducing the influence from an outside environment.